Molecule mapping of HR8799b using OSIRIS on Keck: Strong detection of water and carbon monoxide, but no methane

Context. In 2015, Barman et al. (ApJ, 804, 61) presented detections of absorption from water, carbon monoxide, and methane in the atmosphere of the directly imaged exoplanet HR8799b using integral field spectroscopy (IFS) with OSIRIS on the Keck II telescope. We recently devised a new method to analyse IFU data, called molecule mapping, searching for high-frequency signatures of particular molecules in an IFU data cube. Aims. The aim of this paper is to use the molecule mapping technique to search for the previously detected spectral signatures in HR8799b using the same data, allowing a comparison of molecule mapping with previous methods. Methods. The medium-resolution H- and K-band pipeline-reduced archival data were retrieved from the Keck archive facility. Telluric and stellar lines were removed from each spectrum in the data cube, after which the residuals were cross-correlated with model spectra of carbon monoxide, water, and methane. Results. Both carbon monoxide and water are clearly detected at high signal-to-noise, however, methane is not retrieved. Conclusions. Molecule mapping works very well on the OSIRIS data of exoplanet HR8799b. However, it is not evident why methane is detected in the original analysis, but not with the molecule mapping technique. Possible causes could be the presence of telluric residuals, different spectral filtering techniques, or the use of different methane models. We do note that in the original analysis methane was only detected in the K-band, while the H-band methane signal could be expected to be comparably strong. More sensitive observations with the JWST will be capable of confirming or disproving the presence of methane in this planet at high confidence.Comment: 5 pages, 5 figures and 2 tables, accepted by A&

Probing deviations from General Relativity with the Euclid spectroscopic survey

We discuss the ability of the planned Euclid mission to detect deviations from General Relativity using its extensive redshift survey of more than 50 Million galaxies. Constraints on the gravity theory are placed measuring the growth rate of structure within 14 redshift bins between z=0.7 and z=2. The growth rate is measured from redshift-space distortions, i.e. the anisotropy of the clustering pattern induced by coherent peculiar motions. This is performed in the overall context of the Euclid spectroscopic survey, which will simultaneously measure the expansion history of the universe, using the power spectrum and its baryonic features as a standard ruler, accounting for the relative degeneracies of expansion and growth parameters. The resulting expected errors on the growth rate in the different redshift bins, expressed through the quantity f\sigma_8, range between 1.3% and 4.4%. We discuss the optimisation of the survey configuration and investigate the important dependence on the growth parameterisation and the assumed cosmological model. We show how a specific parameterisation could actually drive the design towards artificially restricted regions of the parameter space. Finally, in the framework of the popular "\gamma -parameterisation", we show that the Euclid spectroscopic survey alone will already be able to provide substantial evidence (in Bayesian terms) if the growth index differs from the GR value \gamma=0.55 by at least \sim 0.13. This will combine with the comparable inference power provided by the Euclid weak lensing survey, resulting in Euclid's unique ability to provide a decisive test of modified gravity.Comment: 18 pages, 15 figures, accepted by MNRA

Molecular dynamics simulation of the nanoindentation process in Cr/CrN and (Cr/CrN)2 thin films

Molecular dynamics (MD) simulations were carries out for studying the influenceof nanoindentation in the atomistic deformation mechanisms of Cr/CrN and(Cr/CrN)2 coatings with BCC and FCC crystalline structures for Cr and CrN,respectively. The Morse potential was employed in order to determine the atomicinteraction forces of the Cr-Cr and Cr-N atoms. A non-deformable potential solidsphere was implemented for determining the role of the nanoindenter. The OliverParr method (OP) was used to obtain the hardness and elastic modulus of the Cr/CrN and (Cr/CrN)2 layers, resulting in values of 18 and 20 GPa for Cr/CrN and (Cr/CrN)2, respectively. The Cheng method was used for correcting the hardness values obtained by the OP method. The Cheng correction showed higher hardness values since it avoids the influence of the scale effect. Regarding the elasticity modulus, Cr/CrN and (Cr/CrN)2 exhibited values of 217.86 GPa and 258.9 GPa, respectively. Simulations of the temperature influence on the hardness were carried out over a range of 300-1000 K. Results indicate that the hardness decreased as a function of the temperature.Fil: Amaya Roncancio, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich". Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Instituto de Física Aplicada "Dr. Jorge Andrés Zgrablich"; ArgentinaFil: Arias Mateus, D. F.. Universidad Católica de Pereira; ColombiaFil: Segura Giraldo, B.. Universidad Nacional de Colombia; ColombiaFil: de la Roche, J.. Universidad Nacional de Colombia; ColombiaFil: Restrepo Parra, E.. Universidad Nacional de Colombia; Colombi

Why every observatory needs a disco ball

Commercial disco balls provide a safe, effective and instructive way of observing the Sun. We explore the optics of solar projections with disco balls, and find that while sunspot observations are challenging, the solar disk and its changes during eclipses are easy and fun to observe. We explore the disco ball's potential for observing the moon and other bright astronomical phenomena.Comment: 6 pages, 7 figures. Submitted to Physics Education. Comments welcom

Cerramientos bioclimáticos para climas cálidos húmedos: la cuarta vivienda

In intertropical latitudes such as Venezuela with hot humid climates, building envelopes must reduce influence of solar radiation, and in these, roofs and windows must receive special attention. Venezuela is also the country with the highest energy consumption per capita in Iberoamérica, much of which is generated by air conditioning systems in residential buildings, and Maracaibo and the surrounding lake basin have some of the highest temperature and humidity values in Venezuela, which increase energy consumption even more. A bioclimatical house for this climate is proposed. This building incorporates principles from traditional indigenous, colonial and oil company houses in the Maracaibo lake basin to generate a new prototype, called the Fourth House.En climas cálidos húmedos como es el caso de grandes regiones de Venezuela, las envolventes deben reducir la influencia de la radiación solar y, por lo tanto, deben recibir atención especial. Venezuela es también el país con más alto consumo energético per capita en Iberoamérica, generado en su mayor parte por el uso de sistemas de aire acondicionado en las edificaciones residenciales. En Maracaibo y en los alrededores del Lago de Maracaibo se registran los valores más altos de temperatura y humedad en Venezuela, lo que incrementa, aún más, el consumo energético de las viviendas de estas regiones. La minimización del impacto de la radiación solar para lograr la reducción del consumo energético con un mayor bienestar térmico ha sido precisamente uno de los objetivos perseguidos con el desarrollo de una nueva vivienda bioclimática para la región del lago de Maracaibo. Esta incorpora principios de las tres viviendas bioclimáticas previas existentes en esa región: el palafito o vivienda tradicional indígena, la vivienda colonial republicana y la vivienda petrolera. Es por ello que esta vivienda ha sido llamada la Cuarta Vivienda

Telomere lengths in human oocytes, cleavage stage embryos and blastocysts

Telomeres are repeated sequences that protect the ends of chromosomes and harbour DNA-repair proteins. Telomeres shorten during each cell division in the absence of telomerase. When telomere length becomes critically short, cell senescence occurs. Telomere length therefore reflects both cellular ageing and capacity for division. We have measured telomere length in human germinal vesicle (GV) oocytes and pre-implantation embryos, by quantitative fluorescence in-situ hybridisation (Q-FISH), providing baseline data towards our hypothesis that telomere length is a marker of embryo quality. The numbers of fluorescent foci suggest that extensive clustering of telomeres occurs in mature GV stage oocytes, and in pre-implantation embryos. When calculating average telomere length by assuming that each signal presents one telomere, the calculated telomere length decreased from the oocyte to the cleavage stages, and increased between the cleavage stages and the blastocyst (11.12 vs 8.43 vs 12.22kb respectively, p<0.001). Other methods of calculation, based upon expected maximum and minimum numbers of telomeres, confirm that telomere length in blastocysts is significantly longer than cleavage stages. Individual blastomeres within an embryo showed substantial variation in calculated average telomere length. This study implies that telomere length changes according to the stage of pre-implantation embryo development

High-precision multi-band measurements of the angular clustering of X-ray sources

In this paper we present the two-point angular correlation function of the X-ray source population of 1063 XMM-Newton observations at high Galactic latitudes, comprising up to ~30000 sources over a sky area of 125.5 sq. deg, in three energy bands: 0.5-2 (soft), 2-10 (hard), and 4.5-10 (ultrahard) keV. We have measured the angular clustering of our survey and find significant positive clustering signals in the soft and hard bands, and a marginal clustering detection in the ultrahard band. We find dependency of the clustering strength on the flux limit and no significant differences in the clustering properties between sources with high hardness ratios and those with low hardness ratios. Our results show that obscured and unobscured objects share similar clustering properties and therefore they both reside in similar environments, in agreement with the unified model of AGN. We deprojected the angular clustering parameters via Limber's equation to compute their typical spatial lengths. From that we have inferred the typical mass of the dark matter haloes in which AGN at redshifts of ~1 are embedded. The short AGN lifetimes derived suggest that AGN activity might be a transient phase that can be experienced several times by a large fraction of galaxies throughout their lives.Comment: 14 pages, 9 figures, accepted for publication in Astronomy and Astrophysic

An intrinsically labile α-helix abutting the BCL9-binding site of β-catenin is required for its inhibition by carnosic acid.

Wnt/β-catenin signalling controls development and tissue homeostasis. Moreover, activated β-catenin can be oncogenic and, notably, drives colorectal cancer. Inhibiting oncogenic β-catenin has proven a formidable challenge. Here we design a screen for small-molecule inhibitors of β-catenin's binding to its cofactor BCL9, and discover five related natural compounds, including carnosic acid from rosemary, which attenuates transcriptional β-catenin outputs in colorectal cancer cells. Evidence from NMR and analytical ultracentrifugation demonstrates that the carnosic acid response requires an intrinsically labile α-helix (H1) amino-terminally abutting the BCL9-binding site in β-catenin. Similarly, in colorectal cancer cells with hyperactive β-catenin signalling, carnosic acid targets predominantly the transcriptionally active ('oncogenic') form of β-catenin for proteasomal degradation in an H1-dependent manner. Hence, H1 is an 'Achilles' Heel' of β-catenin, which can be exploited for destabilization of oncogenic β-catenin by small molecules, providing proof-of-principle for a new strategy for developing direct inhibitors of oncogenic β-catenin

SILAC-based proteomic quantification of chemoattractant-induced cytoskeleton dynamics on a second to minute timescale

Cytoskeletal dynamics during cell behaviours ranging from endocytosis and exocytosis to cell division and movement is controlled by a complex network of signalling pathways, the full details of which are as yet unresolved. Here we show that SILAC-based proteomic methods can be used to characterize the rapid chemoattractant-induced dynamic changes in the actin–myosin cytoskeleton and regulatory elements on a proteome-wide scale with a second to minute timescale resolution. This approach provides novel insights in the ensemble kinetics of key cytoskeletal constituents and association of known and novel identified binding proteins. We validate the proteomic data by detailed microscopy-based analysis of in vivo translocation dynamics for key signalling factors. This rapid large-scale proteomic approach may be applied to other situations where highly dynamic changes in complex cellular compartments are expected to play a key role